Effect of rare earth oxide on microstructure and high temperature oxidation properties of laser cladding coatings on 5CrNiMo die steel substrate

•Rare earth oxide Y2O3 refined the reinforcements and purified the coatings.•The cumulative oxidation mass of cladding coating is decreased by addition of Y2O3.•Y2O3 promotes the formation of compact of oxide film and hinders the further oxidation of gaseous oxygen. In situ multiple ceramic reinforced Fe-based composite coatings with Y2O3 were fabricated on 5CrNiMo die steel by laser cladding processing. The influence of rare earth oxide Y2O3 on the microstructure and high temperature oxidation properties of cladding coating was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS) and high-temperature oxidation resistance test. The results showed that ceramic particles and microstructure of coatings can be fined by rare earth oxide Y2O3. Volume fraction of ceramics increased with the increase of Y2O3. The high temperature oxidation resistance of the coatings was improved by Y2O3. As well as, the cumulative oxidation mass of cladding coating with 2 wt% Y2O3 decreased by one-third of the coating without addition of Y2O3. A dense layer was formed on the coating with Y2O3, preventing the coating from being oxidized.